Not every author wants to actively advocate your political agenda, and not every author agrees with it.
Not every essay can be a scholarly paper with full references to defend its statements.
Consider this quote from the essay: """Other toxic stereotypes used to make lower-class people into jokes include crude language or behavior, having “too many” children, and being unintelligent. The United States has “hick” or “white trash” stereotypes that are often used to depict low-income white people."""
Here's a 50 minute lecture on "White Trash: The 400-Year History of Class in America" which expands on this one topic - https://www.youtube.com/watch?v=_cPII2l-K4s presented by the author of a book of the same name. I found it quite insightful.
That the author fails to justify every point might be because they appear to me to be well-known - and not based simply on a political agenda, but backed by sociological research.
The exercise of building a sociology authority itself would be enlightening if made transparent. Given the well-publicized inability of social science research results to be replicated [citation needed], it might be a very short book.
Google Scholar says there are over 2,000 results in 2020 so far for "classism in america" - https://scholar.google.com/scholar?as_ylo=2020&q=classism+in... .
Now, some are about Latin America, and some historical, so I refined the search by adding "redneck" - https://scholar.google.com/scholar?as_ylo=2020&q=classism+in... . Still has 41 results.
The first (and most relevant of the ones linking to the papers) was https://www.tandfonline.com/doi/pdf/10.1080/00377317.2020.17... , "Classless: Classism in Social Work Practice and the Example of White Rural Proverty". Some quotes:
> It is not unusual to hear the pejorative phrases, “whitetrash,” “redneck” and “hick” uttered with surprising ease by self-described progressives and academics alike (Wray,2006). ...
> White rural poverty provides an example of classism, uncolored by racism and racial oppression. To expressly highlight white poverty challenges the myth of universal white privilege and demonstrates the potency of class standing as a defining social factor allowing for either belonging or disenfranchisement (Winders,2003). However, the culturally sanctioned disdain toward “white trash” signals both loathsome attitudes toward the poor and reveals implicit racial biases toward the assumed and expected superiority of whiteness (Wray,2006). ...
Your comment about "results to be replicated" must surely add the qualifier "many" or even "most". It's certainly not true that all of social science research is unable to be replicated.
Similarly, your comment didn't specify anything about what this political viewpoint might be, nor any reasons why you think this article is based on such a viewpoint.
I don't think the author is presenting these ideas based on "any negative depiction of poor people is bad". It's more as a pointer on these common tropes that exist in storytelling, and some of the implied unrealistic assumptions that underly them.